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When clay soils expansion occurs, foundation movements can result. It has been my experience that whenever an older home (say 15 to 20 years or more) that is constructed on highly plastic clay suddenly experiences cracking in brick or sheetrock, after many years of crack-free service, and there’s no other obvious answer to the problem, it’s probably related to drying shrinkage of underlying expansive clay subsoils. These subsoils probably remained wet each year, throughout the life of the home. Or, at least, the moisture change that did occur each year in the underlying massive clay soil was not sufficient to cause enough building distortion to, in turn, cause building material cracking. If the home suddenly develops cracks, however, there’s probably been some major change in the drainage conditions or landscape surrounding the home.

Foundation movements can result when clay soils shrinkage occurs.  A home-buyer transferring into the Huntsville metropolitan area once asked me, “What is the most common residential foundation problem that you see in your home inspection business?” I answered, “Differential foundation settlements (movements) due to expansive clay soils.” “Not so much expansion,” I explained, “but the opposite actually-or what we commonly call ‘shrinkage.’”